Powerful Lasers Mimic Supernova Explosions in the Lab

by Kelly Dickerson | June 07, 2014 07:34am ET

Although most stellar explosions are fairly symmetrical, the supernova remnant W49B has an odd shape that could have resulted from the interaction of its magnetic field with its parent star.Credit: X-ray: NASA/CXC/MIT/L.Lopez et al; Infrared: Palomar; Radio: NSF/NRAO/VLA

Supernovas are among the biggest blasts in the known universe. The star explosions release a burst of radiation that can outshine an entire galaxy and span across several light-years. But now, scientists have figured out how to fit supernovas in a lab ... with lasers.

Researchers have simulated these violent stellar eruptions in a scaled-down fashion to help solve a mystery about the shape of supernova leftovers.

When a star goes supernova, it leaves behind a skeleton made of expanding dust and gas that astronomers call a remnant. Some supernova remnants, like the famous Cassiopeia A, do not expand uniformly through space, but instead produce puzzling shapes filled with knots and twists. [Supernova Photos: Great Images of Star Explosions]

To investigate why these bizarre kinks form, scientists from the University of Oxford designed a method to recreate supernova explosions with lasers 60,000 billion times more powerful than a regular classroom laser pointer. Using this technique, the team of scientists, led by Gianluca Gregori, could observe the blast up close instead of from thousands of light-years away.

Scientists are using lasers to recreate supernova explosions to better understands how stars die. In this image, laser beams illuminate a small carbon rod and launch an asymmetric shock inside a chamber filled with argon gas. An imaging technique records the event (background blue-black hues) while a computer simulation then predicts the electron density in red-blue hues.Credit: University of Oxford

For their experiments, the scientists focused the laser beams on a thin carbon rod barely thicker than a strand of hair that was located inside a gas-filled chamber. The lasers baked the chamber to over 1 million degrees Celsius (1.8 million degrees Fahrenheit). The intense heat caused the carbon rod to explode, and the blast zipped through the low-density gas in the chamber, just like material from an exploding star speeds through space.

Supernovas can happen two different ways. The first kind occurs when one star sucks matter away from another nearby star. As the star gets bigger, it becomes unstable and explodes. Supernovas also happen near the end of a star's life. As the star's core runs out of fuel, it starts sucking in the surrounding matter. The core gets so heavy that it collapses under its own gravitational force and explodes.

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The scientists had suspected that the strange shapes seen in supernova remnants come from patches of dust and clouds that interrupt the speeding blast material and create strong magnetic fields around the star remnant. To simulate the dust and gas a real supernova blast would encounter, the researchers placed a plastic grid in the chamber that would block some of the heat from the explosion as it expanded; this created turbulence within the chamber.

"The experiment demonstrated that as the blast of the explosion passes through the grid, it becomes irregular and turbulent, just like the images from Cassiopeia," Gregori, professor of physics at the University of Oxford, said in a statement.

The researchers, who published their findings in the journal Nature Physics on June 1, also confirmed that the turbulence the blast experiences increases the strength of the magnetic fields often found in supernova remnants. The team thinks their experiments could provide some insight into how magnetic fields were first created.

The study of supernovas has already revealed valuable information about the history of the universe. The explosions have provided evidence that the universe is expanding, and they constitute a record of how materials spread around space; elements from exploded stars are found on Earth, and the material a star spews when it explodes can become the source of a new star.